This proposal will further investigate a unique class of compounds mercaptoalkylguanidines (MAGs) which have been shown to inhibit the inducible isoform of nitric oxide synthetase, a enzyme which is overexpressed in various forms of inflammation and produces cytotoxic amounts of the free radical nitric oxide and scavenges peroxynitrite a reactive toxic oxidant produced in inflammation. The specific aim of this proposal is to establish whether one of these MAGs, namely MEG, prevents the course of the disease development in a ligature induced periodontitis rat model. The efficacy of these MEGs will be measured by evaluating the levels of periodontal attachment histomorphometrically, levels of peroxynitrate and levels of the inducible isoforms of nitric oxide synthetase (iNOS) on both MEG treated and untreated rats with periodontitis. PROPOSED COMMERCIAL APPLICATION: According to a recent survey, 44 percent of the US population had gingivitis. The market for medicated toothpastes and other dental products is well over $100 million Per annum in the US only.